Furnace



R. S. BROWN Nov. 16, 1937.

FURNACE Filed Deo. 21, 1955 @A INVENTOR Patented Nov. 16, 1937 PATENT oFFicE FURNACE Roger Stuart Brown, Upper Montclair, N. J., assignor of one-half to Bertram J. Sayles, Pittsburgh, Pa.

VApplication December 21, 1935, Serial No. 55,639

6 Claims.

This invention relates to a furnace and in particular to a metallurgical or heat treating furnace.

Heat treating furnaces having cylindrical work supporting members have come into wide use in recent years. Such members operate under eX- treme temperature conditions and this fact has imposed serious limitations upon the design of furnaces and required the use of costly heat resisting alloys. The maximum dimension of such furnaces measured along the cylindrical member has been limited by the permissible deflection of the member acting as a beam to sustain the material being treated, and a furnace design at best has been more or less of a compromise between size, operating temperature, and the cost of the cylindrical work supporting members, as well as the permissible maximum stress in the member itself.

I have invented a furnace, the design of which is not restricted by the aforementioned limitations in that the maximum dimension along the cylindrical work supporting member may be increased withcut increasing the maximum stress in the member itself above values now used. This also permits furnaces to be operated at higher temperatures and permits a reduction in the size and weight of the work supporting members for a given load, and thus reduces the first 3o cost as well as the maintenance cost. likewise,

heavier loads may be carried by the work supporting members if their dimensions are the same as have been employed heretofore.

In accordance with my invention, I provide a 35 cylindrical work supporting member mounted for rotation within a heating enclosure, with trunnions or axial projections extending outwardly Vcf the ends thereof. I provide means cooperating with these projections for exerting a negative 40 moment on the cylindrical work supporting member. The .negative moment may be exerted by counterweights or by thruster means including a spring or a iiuid pressure cylinder and piston.

The invention is particularly applicable to that 45 form of furnace in which the work is disposed in a cylindrical retort which is rotated during the heating.

For a complete understanding of the invention, reference is made to the accompanying drawing, 50 which is to be read in connection with the following detailed description of a preferred embodiment ofthe invention.

In the drawing:- Figs. 1a and 1b together constitute a longi- 55 tudinal sectional view through a furnace comprising a cylinder rotatably mounted in a heating chamber, and Fig. 2 is a moment diagram.

Referring now in detail to the drawing,

Figs. la and 1b show a tube type furnace 36 comprising a cylindrical retort 3'! rotatably mounted on roller bearings 38 and 38 within a heating enclosure 39. The work being treated in the furnace is indicated at 40. The retort 3l has end covers 4i provided with axial extensions or stub shafts 42. The end covers are preferably 10 bolted onto flanged collars welded to the end of the cylindrical retort. The peripheries of the collars rest on the bearings 38 and 3S for rotatably supporting the retort 31. The rollers of the bearings 38 are fianged to resist axial thrust 15 while the rollers of the bearings 38 are plain, and thus permit expansion of the retort when heated. Bearings 43 at the ends of the extensions 42 suspend counterweights 44 for exerting a negative moment on the retort 3l over 20 the bearings 38. The bearings 43 comprise simply sleeves or bushings disposed over the reduced ends of the shafts 42, having chain links attached thereto for supporting the counterweights 4Q. Jacks 45 lift the weights 44 tem- 25 porarily to permit the covers 4l to be removed when the work is to be inserted into or removed from the retort. Fig. 2 is a graphic comparison between the moment curves of a retort embodying the present invention and a conventionally mounted retort. The diagram shows that the invention permits a material reduction of the maximum stress in the cylindrical body of the retort. This means that a retort of a given size can carry a greater load without exceeding a given maximum stress. Conversely, retorts can be constructed in longer lengths, for the same load capacity, than has been possible heretofore. The invention makes possible the design of cylindrical work supporting members for furnaces operating at temperatures as high as 2100 F. and reduces the amount of deflection, distortion and warpage of the member. Since a Smaller member can be used for a given span or load, in accordance with the invention, the first cost is 45 reduced and the maintenance cost likewise.

The foregoing advantages of my invention are to be found not only in the specific forms of structure herein illustrated and described, but the invention may also be embodied in other forms without sacrificing these advantages or departing from the spirit of the invention as set forth in the appended claims.

I claim:-

1. In a furnace, a tubular retort, bearings supto said cover and said flange engaging one of said bearings.

4. In a furnace, a tubular retort, covers Yre- -Y movably secured to the ends of the retort, a shaft extending outwardly from each cover axially of said retort, and a counterweight suspended from each shaft.

5. In a furnace, a tubular retort, bearings sup,-

porting the retort for rotation, a shaft extending axially from at least one end of the retort and rigidly connected to the body of the retort so as to transmit a bending moment thereto, and means for applying a negative bending moment to said shaft at a point spaced outwardly beyond the bearing adjacent said end of the retort, whereby to reduce the bending moment in the body of the retort.

6. In a furnace, a tubular retort, bearings supporting the retort in the furnace for rotation, a

removable end cover for the retort rigidly secured thereto so as to transmit a bending moment to the retort, a cantilever member extending from said cover, and means for applying a negative bending moment to said member and thence to said retort.

' ROGER STUART BROWN. 

